1. Field of the Invention
The present invention relates to power supply systems and more particularly, to an induction type power supply system with synchronous rectification control for data transmission, which comprises a supplying-end module, and a receiving-end module, which receives power supply from the supplying-end coil and provides a feedback data signal to the supplying-end coil during power supply transmission subject to the operation of a rectifier and signal feedback circuit of the receiving-end module that breaks off electric current transiently to change the load characteristics of the receiving-end coil of the receiving-end module, allowing transmission of the feedback data signal without causing power loss.
2. Description of the Related Art
In an induction type power supply system, the most important technique is to identify the object on the supplying-end coil. The power transmitting operation of the supplying-end of an induction type power supply system is similar to the operation of an electromagnetic induction stove for cooking purpose. Directly emitting electric energy onto a metal object will make the metal object hot, leading to unexpected risk. Technique to identify target by the supplying-end was developed to eliminate the aforesaid problem and has been validated workable. This technique enables the coil at the receiving-end to provide a feedback data signal to the coil at the supplying-end during transmission of power supply from the supplying-end to the receiving-end. However, it is difficult to stabilize the transmission of a feedback data signal from the coil at the receiving-end to the coil at the supplying-end during transmission of power supply from the supplying-end to the receiving-end. The signal carrier under the transmission of a high power will be interfered with various noises. Further, this feedback data signal transmission method is performed subject a frequency modulation control system, the operating frequency of the main carrier is not constant. To solve data signal transmission problem under a high power, a wireless communication channel, such as Bluetooth, RFID or Wi-Fi, may be used with power transmission induction coils. However, the use of an extra wireless communication module greatly increases the cost of the induction type power supply system.
Further, there are some technical problems to transmit data signal through power transmission induction coils. Data signal transmitting and receiving operations through power transmission induction coils are same as the application of RFID technology, i.e., the coil at the supplying-end transmits a main carrier to the coil at the receiving-end, and then a circuit at the receiving-end controls the load at the coil to provide a feedback data signal. Therefore, it is a one-way transmission in conventional induction type power supply designs, i.e., power energy (LC oscillator main carrier) is transmitted by the supplying-end to the receiving-end, and then the receiving-end provides a feedback data code to the supplying-end. The energy received by the receiving-end may vary in strength without any communication component. The transmission of the feedback data code can be done only after the receiving-end has been kept in proximity to the supplying-end to receive sufficient electric energy. When the supplying-end provides no power supply to the receiving-end, the receiving-end cannot provide a feedback data code to the supplying-end. This design is not a complete communication system; however, it is practical in an induction type power supply system to satisfy the functional requirements of the system. Normally, after recognition of the identification of the target, the supplying-end starts to transmit power supply, and makes proper adjustment subject to a feedback signal from the receiving-end.
The power receiving and data feedback architecture at the receiving-end of conventional induction type power supply systems may be a resistive or capacitive type design. In a resistive type design, the modulation of a feedback signal comes from passive RFID techniques. By means of using the impedance switching function of the coil at the receiving-end, the feedback signal is provided to the coil at the supplying-end. Further, to reduce power loss during the transmission of a feedback data signal under a high power environment, capacitive feedback signal modulation technique was created. Either of the aforesaid resistive type and capacitive type designs will increase the power output of the supplying-end during signal modulation, and the power loss will be relatively increased when the number of times of signal modulation or the modulating time is increased. This power loss problem of conventional induction type power supply systems is directly contrary to the basic principle of energy saving of modern products. Further, in the aforesaid designs, a current impact may be produced at the circuits of the receiving-end during signal modulation, causing damage to power converting components or instable power supply.
Therefore, it is desirable to an economic induction type power supply system, which ensures a high level of power supplying stability, facilitating transmission of feedback data signal by the receiving-end to the supplying-end without causing power loss.